Whilst the following discussion concerns screen saving devices for laptop display and screens, it is to be understood that the same principles apply to any displays using pixels or other display elements, especially electronic displays using display elements to form an image on a display screen. Such displays may be components of computers, mobile phones, electronic score boards or electronic billboards.
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So-called screen saving devices for monitors or screens used in electronic display devices are in common use. Such screen saving devices are commonly used for monitors connected to computers and portable computers, such as laptop. One of the purposes of screen saving devices is to conserve energy expended in maintaining a constant image on the screen or monitor.
In portable computers, such as laptop, an array of pixels (often made of liquid crystals) is arranged behind the display screen. An electric pulse is sent to the array to activate or deactivate the pixels to form the image and a backlight shines light through the pixels, producing an image on a display screen. The electric pulse trust be sent quite frequently to the array in order to maintain the image on the display screen. This is known as “refreshing” the image. Most standard laptop need to refresh the image up to 75 times per second. This refreshing process uses a substantial amount of the battery power of the laptop, thereby reducing usage time. In addition, the whole image has to be refreshed even though only a small portion of the whole image on the display screen may need to change, such as, for example, the movement of a cursor or mouse arrow.
Conventional screen saving devices tend to resort to switching off the backlight after a certain time period passes in which the laptop screen is inactive. However, theses conventional screen saving devices do not operate when the laptop is in use. Consequently, they do not deal with conserving battery power expended by refreshing the image on the display screen.